Cook all first three ingredients to 3000F , but if you don't have a thermometer as well, rely on the good old water test.
Once your sugar starts to thicken, intermittently, drop a drop ( pun intended) into a small bowl of water. If it's still soft, it isn't yet ready.
If it hardens up instantly take your sugar down from the fire and allow a few seconds pass for it to stop bubbling.
At this stage you can stir in your flavouring or use straight away.
Always ensure your ice cavity is properly greased with some sort of food oil before pouring in your hot sugar. I learned the hard truth about setting hard candy the hard way. 😅 hehehe